12 deaths reported in Canadian Listeria outbreak

Aug 26, 2008 (CIDRAP News) – A Listeria outbreak linked to a Maple Leaf Foods meat product plant in Toronto has expanded to 26 cases, and 12 people have died, though it was not yet clear how many of the deaths were directly due to the illness, Canadian officials announced yesterday.

In a statement, the Public Health Agency of Canada (PHAC) said 26 cases involving the outbreak strain of Listeria monocytogenes had been confirmed in Quebec, Ontario, Saskatchewan, and British Columbia.

Of the 26 cases, "there are 12 deaths associated with the outbreak strain (11 in Ontario and one in B.C.)," the agency said. "Six of these deaths, reported from Ontario, have linked listeriosis as the underlying or contributing cause of death. In the remaining deaths, the role that listeriosis may have played remains under investigation." The deaths occurred over the past several weeks.

The agency said another 29 suspected cases were under investigation and predicted that the numbers of both suspected and confirmed cases would increase in the days ahead. All the suspected cases are known to be listeriosis, but test results were awaited to determine how many involve the outbreak strain, officials said. The agency has said the incubation period for listeriosis can be as long as 70 days.

The outbreak prompted Maple Leaf Foods on Aug 20 to announce a recall of products made on two production lines at its Bartor Road plant in Toronto. On Aug 23 the company expanded the recall to include all products produced at the plant since January. Products made there carry the establishment number 97B on their labels. It was not immediately clear if any products from the facility are exported to the United States.

The PHAC confirmed the connection between the outbreak and Maple Leaf products on Aug 23. Testing of three product samples showed that two were contaminated with the outbreak strain, while the third had contamination that differed slightly from that strain, the agency said, adding that it expected to learn more this week.

L monocytogenes can grow on refrigerated meat and cause serious illness in pregnant women, elderly people, and others with weak immune systems. Largely because of the risk of listeriosis, the US Food and Drug Administration (FDA) says these groups should not eat hot dogs or deli meats unless they are reheated, nor should they eat refrigerated meat spreads, refrigerated smoked seafood unless cooked, or products containing unpasteurized milk.

Symptoms of the illness include fever, muscle aches, and sometimes nausea or diarrhea, according to the PHAC.

According to a Reuters report published yesterday, a Maple Leaf official said the company was unlikely to be able to determine exactly how its meat was contaminated, because Listeria organisms are common and pervasive.

The outbreak apparently is one of the larger ones in North America in recent years. Records indicate that the last high-profile Listeria outbreak in the United States occurred in the Northeast in the fall of 2002 and involved at least 53 cases and 8 deaths in nine states.